The electrical systems in residential, commercial and industrial applications usually include a panelboard for receiving electrical power from a utility source. The power is then routed through overcurrent protection devices to designated branch circuits supplying one or more loads. These overcurrent devices are typically circuit interrupters such as circuit breakers and fuses which are designed to interrupt the electrical current if the limits of the conductors supplying the loads are surpassed. Interruption of the circuit reduces the risk of injury or the potential of property damage from a resulting fire.
Circuit breakers are a preferred type of circuit interrupter because a resetting mechanism allows their reuse. Typically, circuit breakers interrupt an electric circuit due to a trip condition such as a current overload or ground fault. The current overload condition results when a current exceeds the continuous rating of the breaker for a time interval determined by the trip current. The ground fault trip condition is created by an imbalance of currents flowing between a line conductor and a neutral conductor such as a grounded conductor, a person causing a current path to ground, or an arcing fault to ground.
An example of a ground fault interrupter is a fast acting circuit breaker that disconnects equipment from the power line when some current returns to the source through a ground path. Under normal circumstances all current is supplied and returned within the power conductors. But if a fault occurs and leaks some current to ground, then the ground-fault circuit interrupter (GFCI) will sense the difference in current in the phase and neutral power conductors. If the fault level exceeds the trip level of the GFCI, then the circuit will be disconnected. The trip level for protection of personnel is usually in the range of about 4 mA to 6 mA. The trip level for the protection of equipment is usually about 30 mA.
GFCIs commonly have an electronic circuit board or discrete components that are interconnected by multi-strand wires. For example, a transformer is often used to sense the current imbalance between phase and neutral power lines connected to wires which are positioned within the transformer's magnetic field or transformer window. A change in the position of wires within the magnetic field affects the transformer's ability to sense current flow and generate a reliable signal. Accordingly, a problem arises to ensure the accuracy and repeatability of the wires' position during assembly. The wires' flexibility also increases the difficulty of locating their position with the precision required to use automated equipment for quality assurance testing. Furthermore, a short circuit current often generates a high magnetic force which can deflect the wires, changing their position and affecting their ability to sense current flow.
The prior art as exemplified in U.S. Pat. No. 4,568,899 issued to May et al. discloses a ground fault accessory for a circuit breaker. Wires are used as the leads and connectors between a trip circuit and a neutral conductor or to other components such as a circuit board. The wires cause several problems. Routing of the wires during assembly of the circuit breaker requires a disproportionate amount of time and expense and complicates automation of the assembly process. Placement of the wires in close proximity to one another can also lead to arcing during high voltage surges. Any damage to the wiring insulation can lead to a dielectric breakdown and a short circuit condition.
The need arises to overcome the problems associated with using wire for making electrical connections between components and terminals of a ground fault module. The present invention provides rigid, solid conductors between the terminals of a ground fault module. The assembly of the ground fault module with the inventive conductors is accurate and reproducible, effectively preventing arcing with other components of the module.